#region Namespaces

using System;
using System.Collections.Generic;
using System.IO;
using System.Xml;

#endregion

namespace Vibstudio.X4NET.Xml.Linq
{
    public abstract class XNode : XObject
    {
        private static readonly XNodeEqualityComparer eqComparer = new XNodeEqualityComparer();

        private static readonly XNodeDocumentOrderComparer orderComparer = new XNodeDocumentOrderComparer();

        internal XNode()
        {
        }

        public static XNodeDocumentOrderComparer DocumentOrderComparer
        {
            get { return orderComparer; }
        }

        public static XNodeEqualityComparer EqualityComparer
        {
            get { return eqComparer; }
        }

        public XNode PreviousNode { get; internal set; }

        public XNode NextNode { get; internal set; }

        public static int CompareDocumentOrder(XNode n1, XNode n2)
        {
            return orderComparer.Compare(n1, n2);
        }

        public static bool DeepEquals(XNode n1, XNode n2)
        {
            return eqComparer.Equals(n1, n2);
        }

        public string ToString(SaveOptions options)
        {
            StringWriter sw = new StringWriter();
            XmlWriterSettings s = new XmlWriterSettings
                                  {
                                      ConformanceLevel = ConformanceLevel.Auto,
                                      Indent = options != SaveOptions.DisableFormatting,
                                      OmitXmlDeclaration = true
                                  };

            XmlWriter xw = XmlWriter.Create(sw, s);
            WriteTo(xw);
            xw.Close();
            return sw.ToString();
        }

        public void AddAfterSelf(object content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }
            XNode here = this;
            XNode orgNext = NextNode;
            foreach (object o in XUtil.ExpandArray(content))
            {
                if (o == null || Owner.OnAddingObject(o, true, here, false))
                {
                    continue;
                }
                XNode n = XUtil.ToNode(o);
                Owner.OnAddingObject(n);
                n = (XNode)XUtil.GetDetachedObject(n);
                n.SetOwner(Owner);
                n.PreviousNode = here;
                here.NextNode = n;
                n.NextNode = orgNext;
                if (orgNext != null)
                {
                    orgNext.PreviousNode = n;
                }
                else
                {
                    Owner.LastNode = n;
                }
                here = n;
                Owner.OnAddedObject(n);
            }
        }

        public void AddAfterSelf(params object[] content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }
            AddAfterSelf((object)content);
        }

        public void AddBeforeSelf(object content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }
            foreach (object o in XUtil.ExpandArray(content))
            {
                if (o == null || Owner.OnAddingObject(o, true, PreviousNode, true))
                {
                    continue;
                }

                XNode n = XUtil.ToNode(o);
                Owner.OnAddingObject(n);
                n = (XNode)XUtil.GetDetachedObject(n);
                n.SetOwner(Owner);
                n.PreviousNode = PreviousNode;
                n.NextNode = this;
                if (PreviousNode != null)
                {
                    PreviousNode.NextNode = n;
                }
                PreviousNode = n;
                if (Owner.FirstNode == this)
                {
                    Owner.FirstNode = n;
                }
                Owner.OnAddedObject(n);
            }
        }

        public void AddBeforeSelf(params object[] content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }
            AddBeforeSelf((object)content);
        }

        public static XNode ReadFrom(XmlReader reader)
        {
            return ReadFrom(reader, LoadOptions.None);
        }

        internal static XNode ReadFrom(XmlReader r, LoadOptions options)
        {
            switch (r.NodeType)
            {
                case XmlNodeType.Element:
                    return XElement.LoadCore(r, options);
                case XmlNodeType.Whitespace:
                case XmlNodeType.SignificantWhitespace:
                case XmlNodeType.Text:
                    XText t = new XText(r.Value);
                    t.FillLineInfoAndBaseUri(r, options);
                    r.Read();
                    return t;
                case XmlNodeType.CDATA:
                    XCData c = new XCData(r.Value);
                    c.FillLineInfoAndBaseUri(r, options);
                    r.Read();
                    return c;
                case XmlNodeType.ProcessingInstruction:
                    XProcessingInstruction pi = new XProcessingInstruction(r.Name, r.Value);
                    pi.FillLineInfoAndBaseUri(r, options);
                    r.Read();
                    return pi;
                case XmlNodeType.Comment:
                    XComment cm = new XComment(r.Value);
                    cm.FillLineInfoAndBaseUri(r, options);
                    r.Read();
                    return cm;
                case XmlNodeType.DocumentType:
                    XDocumentType d = new XDocumentType(r.Name,
                                                        r.GetAttribute("PUBLIC"),
                                                        r.GetAttribute("SYSTEM"),
                                                        r.Value);
                    d.FillLineInfoAndBaseUri(r, options);
                    r.Read();
                    return d;
                default:
                    throw new InvalidOperationException(String.Format("Node type {0} is not supported", r.NodeType));
            }
        }

        public void Remove()
        {
            if (Owner == null)
            {
                throw new InvalidOperationException("Owner is missing");
            }

            var owner = Owner;
            owner.OnRemovingObject(this);
            if (Owner.FirstNode == this)
            {
                Owner.FirstNode = NextNode;
            }
            if (Owner.LastNode == this)
            {
                Owner.LastNode = PreviousNode;
            }
            if (PreviousNode != null)
            {
                PreviousNode.NextNode = NextNode;
            }
            if (NextNode != null)
            {
                NextNode.PreviousNode = PreviousNode;
            }
            PreviousNode = null;
            NextNode = null;
            SetOwner(null);
            owner.OnRemovedObject(this);
        }

        public override string ToString()
        {
            return ToString(SaveOptions.None);
        }

        public abstract void WriteTo(XmlWriter writer);

        public IEnumerable<XElement> Ancestors()
        {
            for (XElement el = Parent; el != null; el = el.Parent)
            {
                yield return el;
            }
        }

        public IEnumerable<XElement> Ancestors(XName name)
        {
            foreach (XElement el in Ancestors())
            {
                if (el.Name == name)
                {
                    yield return el;
                }
            }
        }

        public XmlReader CreateReader()
        {
            return new XNodeReader(this);
        }

        public IEnumerable<XElement> ElementsAfterSelf()
        {
            foreach (XNode n in NodesAfterSelf())
            {
                if (n is XElement)
                {
                    yield return (XElement)n;
                }
            }
        }

        public IEnumerable<XElement> ElementsAfterSelf(XName name)
        {
            foreach (XElement el in ElementsAfterSelf())
            {
                if (el.Name == name)
                {
                    yield return el;
                }
            }
        }

        public IEnumerable<XElement> ElementsBeforeSelf()
        {
            foreach (XNode n in NodesBeforeSelf())
            {
                if (n is XElement)
                {
                    yield return (XElement)n;
                }
            }
        }

        public IEnumerable<XElement> ElementsBeforeSelf(XName name)
        {
            foreach (XElement el in ElementsBeforeSelf())
            {
                if (el.Name == name)
                {
                    yield return el;
                }
            }
        }

        public bool IsAfter(XNode node)
        {
            return DocumentOrderComparer.Compare(this, node) > 0;
        }

        public bool IsBefore(XNode node)
        {
            return DocumentOrderComparer.Compare(this, node) < 0;
        }

        public IEnumerable<XNode> NodesAfterSelf()
        {
            if (Owner == null)
            {
                yield break;
            }
            for (XNode n = NextNode; n != null; n = n.NextNode)
            {
                yield return n;
            }
        }

        public IEnumerable<XNode> NodesBeforeSelf()
        {
            if (Owner == null)
            {
                yield break;
            }
            for (XNode n = Owner.FirstNode; n != this; n = n.NextNode)
            {
                yield return n;
            }
        }

        public void ReplaceWith(object content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }

            XNode here = PreviousNode;
            XNode orgNext = NextNode;
            XContainer orgOwner = Owner;
            Remove();
            foreach (object o in XUtil.ExpandArray(content))
            {
                if (o == null || orgOwner.OnAddingObject(o, true, here, false))
                {
                    continue;
                }
                XNode n = XUtil.ToNode(o);
                n = (XNode)XUtil.GetDetachedObject(n);
                n.SetOwner(orgOwner);
                n.PreviousNode = here;
                if (here != null)
                {
                    here.NextNode = n;
                }
                else
                {
                    orgOwner.FirstNode = n;
                }
                n.NextNode = orgNext;
                if (orgNext != null)
                {
                    orgNext.PreviousNode = n;
                }
                else
                {
                    orgOwner.LastNode = n;
                }
                here = n;
            }
        }

        public void ReplaceWith(params object[] content)
        {
            if (Owner == null)
            {
                throw new InvalidOperationException();
            }
            ReplaceWith((object)content);
        }
    }
}